Hybrid vehicles include an e-machine or other alternative power source which works in conjunction with an internal combustion engine to drive the vehicle. The vehicle includes traditional foundation braking and regenerative braking can also be provided by the alternative power source.
Hybrid vehicles recapture braking energy that would otherwise be lost as heat through foundation braking to improve vehicle operational efficiency. When regenerative braking is being performed, it is important that the vehicle operator's braking and handling “feel” be unaffected. To achieve this there should be controlled blending of regenerative and foundation braking such that the vehicle operator can operate the vehicle in a normal and predictable manner. Maintaining this feel for hybrid commercial truck braking systems presents even more challenges. Further, it is important that mechanical safety features be incorporated into the system in the event of a failure of the regenerative braking portion of the brake system.